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Re: lynx-dev Re: LYNX-DEV Unsubscribed posting


From: David Woolley
Subject: Re: lynx-dev Re: LYNX-DEV Unsubscribed posting
Date: Fri, 17 Apr 1998 08:34:44 +0100 (BST)

Jim Spath Wrote:
> 
> On Wed, 15 Apr 1998, David Woolley wrote:
> > > The attached shows that mail.sig.net is rejecting postings from specific
> > > addresses, or accepting from only certain addresses.
> > > Content-Transfer-Encoding: BASE64
> > Oops.  I'm not going to decode it just for this...
> Pity.

OK here it is off the screen.  Please note that I think this was a MIME
violation, as you should only encode the leaf nodes of nested structures.

] ... while talking to mail.sig.net.:
] >>> MAIL From:<address@hidden> SIZE=144
] <<< 550 <address@hidden>... Catch 22-08 - Your host/domain name could not be 
resolved
] 554 address@hidden Service unavailable
] 
] --OAA00673.892500185/SOL.SLCC.EDU
] Content-Type: message/delivery-status
] 
] Reporting-MTA: dns; SOL.SLCC.EDU
] Arrival-Date: Mon, 13 Apr 1998 14:41:21 -0600 (MDT)
] 
] Final-Recipient: RFC822; address@hidden
] Action: failed
] Status: 5.0.0
] Remote-MTA: DNS; mail.sig.net
] Diagnostic-Code: SMTP; 550 <address@hidden>... Catch 22-08 - Your host/domain 
name could not be resolved
] Last-Attempt-Date: Mon, 13 Apr 1998 14:43:04 -0600 (MDT)

> 
> > However the message indicated a reasonable anti-spam measure to reject
> > mail from addresses with no name in the DNS.  These are typical of
> 
> Of course, sol.slcc.edu *is* in the DNS tables, which means it's not being
> rejected as an outlaw site (it hosts the lynx distribution...), but

I don't believe it is rejecting sol.slcc.edu; it is rejecting the IP
address of the SMTP peer, which is not explicitly identified.  I think
it is rejecting it on the MAIL FROM: because it is a (probably sendmail)
customisation and that was the earliest place in the dialogue at which
it was possible to include the checking logic.

550 is the generic service unavailable message that you get for rejections
in the sendmail check_mail etc. rulesets.  The text message, in the case
of sendmail, is provided by the person creating the configuration file.
I think the envelope address is probably part of the hard coded logic here,
although I think it would have been possible to insert the offending address
in the message text.

You would probably need to look at the SMTP logs to at sig.net to find
out where it thought the mail was from.

> because of other reasons.  Scott McGee can post from the same host
> (e.g., http://www.flora.org/lynx-dev/html/month0498/msg00040.html).
> 

The only evidence we have is what was in the envelope address, not the
actual host that established the SMTP connection.  Someone may have their
mailbox on sol.slcc.edu, but be using an MX aware Unix box to actually send
the mail.

It is possible though that the DNS was broken at the time, or that sig.net's
anti-spam code doesn't properly distinguish between a DNS timeout and not
found.

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